Optical properties of silver selenium indate films obtained by the method of pulse laser vaporization

The spectra of transmission and reflection are measured in the region of 0.4–2.5 μm on thin silver selenium indate films obtained by means of pulse laser vaporization. The magnitudes of the refractive index and absorption coefficient are calculated. The energies of interband transitions and the values of crystalline and spin-orbit splitting are determined. The experimental results for the AgInSe₂ films agree with the data for bulk crystals. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 512–514, July–August, 2000.     

Monitoring of wave-like disturbances by means of oblique sounding of the ionosphere

We present the results of experimental studies of ionospheric wave-like disturbances on the basis of oblique chirp sounding data for the mid-latitude paths Cyprus-Rostov-on-Don and Inskip-Rostov-on-Don. Twenty-four-hour measurements were performed in January-May and October–November, 2005 and in January, 2006. The spectral analysis of variations in the maximum observed frequency (MOF) is performed. It is shown that the spectra of the MOF fluctuations have a well pronounced line structure. The amplitude-dominant spectral harmonics are concentrated near the frequencies 0.18–0.8 mHz (20–90-min periods). We give the results of modeling of radio waves propagation in the presence of traveling ionospheric disturbances and compare the calculated and experimental data. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radio.zika, Vol. 49, No. 12, pp. 1015–1029, December 2006.     

Neutron skin effect of some Mo isotopes in pre-equilibrium reactions

The neutron skin effect has been investigated for even isotopes of molybdenum at 25.6 MeV ^{94 − 100}Mo(p, xn) reaction using the geometry-dependent hybrid model of pre-equilibrium nuclear reactions. Here the initial neutron/proton exciton numbers were calculated from the neutron/ proton densities obtained from an effective nucleon–nucleon interaction of the Skyrme type. Initial exciton numbers from different radii of even Mo isotopes were used to obtain the corresponding neutron emission spectra. In this investigation the calculated results are compared with the experimental data as also with each other. The results using central densities in the geometry-dependent hybrid model are in better agreement with the experimental data.     

The spectra of characteristic energy loss by fast electrons and optical functions for different transmitted wave vectors in graphite

Based on the experimental spectra of energy loss by fast electrons in graphite in the range 0–40 eV, the spectra of complete complexes of optical functions, including the dielectric constant, which are decomposed into components, are calculated for the Г – P directions and four values of the transmitted electron wave vector |q|. The data obtained are compared with the known theoretical bands. It is found that in the indirect interband transitions of graphite excited by fast electrons with |q| > 0, a quasigap is opened in the neighborhood of point P, which increases with |q|.     

Effects of energy-spectrum broadening in alloyed semiconductor superlattices

The density of energy states is calculated for alloyed semiconductor superlattices for different excitation levels with cllowance for the effects of screening and fluctuations of impurity concentrations. The influence of the state density tails on spontaneous-emission spectra is investigated for cross-over transitions and in a model without a selection rule for the electron wave vector. Account for the state density tails allows one to describe the longwave wing and shape of spontaneous-emission spectra in accordance with experimental data. Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 711–715, September–October, 1999.     

Characteristic electron loss spectra and electronic structure of thallium chloride

The bands, state densities N(E), and permittivity are theoretically found for TlCl crystals. On the basis of the experimental characteristic electron loss spectra, the spectra of the complete set of optical functions including permittivity and bulk electron loss spectra are calculated and decomposed into components. The obtained data are compared with the well-known theoretical results. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 8–11, June, 2008.     

Optical properties of grooved silicon microstructures: Theory and experiment

The reflection spectra of grooved silicon structures consisting of alternating silicon walls and grooves (air channels) with a period of a = 4–6 μm are studied experimentally and theoretically in the mid-IR spectral range (2–25 μm) upon irradiation of samples by normally incident light polarized along and perpendicular to silicon layers. The calculation is performed by the scattering matrix method taking into account Rayleigh scattering losses in a grooved layer by adding imaginary parts to the refractive indices of silicon and air in grooved regions. The experimental and calculated reflection spectra are in good agreement in the entire spectral range studied. The analysis of experimental and calculated spectra gave close values of the effective refractive indices and birefringence of the studied structures in the long-wavelength spectral region. The values calculated in the effective medium model in the long-wavelength approximation (λ ≫ a) gave considerably understated values. The obtained results confirm the efficiency of the scattering matrix method for describing the optical properties of silicon microstructures.     

<Emphasis Type="Italic">Ab initio</Emphasis> calculation of band absolute intensities in IR spectra

Ab initio calculations in a harmonic approximation of absorption band absolute intensities in infrared spectra were carried out for 3 hydrocarbons and 14 halogenated hydrocarbons. The calculated data were compared with experimental values of the absolute absorption intensities. It is shown that a Hartree–Fock calculation method overestimates significantly (by an average of 66%) the integrated absolute intensities of the fundamental bands in the region 575–4000 cm^–1. The deviation is reduced to 32% in the case of the MP2 method of accounting for electron correlations. Most of the overestimation occurs for bands corresponding to vibrations involving halogen atoms.     

Calculation of polarized IR absorption spectra for trans-1,4-polyisoprenes of various conformations

Polarized IR spectra for two conformations of trans-1,4-polyisoprene (α-and β-gutta-percha) were calculated. The IR dichroism of the absorption bands was calculated for both conformations. The computed results for polarized IR spectra and IR dichroism agree reasonably well with the respective experiment data. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 470–475, July–August, 2008.     

X-ray signatures of cold accretion disks in AGNs

Summary We have calculated, by means of Monte Carlo simulations, the properties of the radiation emerging from an X-ray illuminated cold accretion disk. These calculations can apply to AGNs, for which there is evidence of cold, optically thick matter near the central black hole. The resulting spectra show an intense iron fluorescent line and a high-energy bump above about 10 keV, where the scattering becomes important with respect to the photoabsorption; these features have been observed by GINGA in some bright Seyfert 1 galaxies. Our detailed results are indicative of the type of future observations which would lead to estimates of the geometrical parameters of the disk, its iron abundance and the mass of the black hole. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.